Wireless sensor networking is one of the most exciting and challenging research areas of recent time. The deployment of wireless sensor networks is becoming more common in a wide variety of applications for collecting and disseminating sensitive and important information. As the application of wireless sensor networks increases, security becomes an important concern since any vulnerability in the system may threaten the widespread practical use of wireless sensor networks. Authentication may be described as assuring that a communication device or sensor is what it represents itself to be rather than an impostor that may have malicious intentions.